简介:Precipitationstrengtheningaswellassolutionstrengtheningiskeymechanismforheatresistantsteels.Itisveryimportanttocharacterizetheprecipitatesin9%Crferriteheatresistantsteels,especiallytoshowthenanometer-sizedparticles.Bytransmissionelectronicmicroscopeattachedwithanenergydispersivespectrometeraswellasopticalmicroscope,scanningelectronicmicroscope,themicrostructureandchemicalcompositionofprecipitatesina9%Crheatresistantsteelafterdifferentheattreatmentswereinvestigated.ItwasfoundthatthemicrostructureofnormalizedsamplewasmartensitewithfineNbCandFe3C.Themicrostructureoftemperedsampleistemperedmartensite,andtheremainlyweretwotypesofprecipitates,M23C6withthesizerangeof50-300nmandMXwiththesizeof10-100nm.SuperfineM23C6precipitatedpreferablyonpriorausteniticgrainboundariesandmartensiticlathboundaries,whilenanometer-sizedMXprecipitatesweredistributedrandomly.Aftershort-termcreep,Lavesphaseformedalonggrainboundariesofthe9%Crsteel,andM23C6andMXprecipitateswerefoundtobecomecoarser.Moreinformationaboutprecipitatesinthe9%Crsteelhadbeenexhibitedbyatomicforcemicroscopy.Thereby,distribution,sizeandshapeoftheprecipitatesaswellastheircompositionsandstructureswererevealed.
简介:StudyontheavoidanceresponseofPenaeuschinensistoheavymetals(Pb,Cr,Zn)andheavymetalmixtures(Pb-Cr,Pb-Zn)iscarredoutusingaY-modelavoidanceapparatus.Theconcentrationscalculatedtoinduce50%avoidanceratebyPenaeuschinensisare11.4,33.2and238.1mg/LforPb,CrandZn,respectively.MixturesofPb-CrandPb-ZnproduceadditiveeffectintheavoidancetestusingPenaeuschinesis.ButwhenthemixedPb-Znsolutionhas0.5toxicunitPband0.5toxicunitZn,themixtureseemstohavesynergisticeffect.
简介:Theexchangecouplingattheferromagnetic/antiferromagnetic(FM/AFM)interfaceisinfluencedbyboththemagneticstructureandthecrystallinemicro-structure.Co/FeMn/Cothinfilmswith0.4nmPtspacerlayerinsertedintotheCo/FeMnandFeMn/Cointerfacerespectivelyweredepositedbymeansofmagnetronsputtering.ThetwointerfacesuponandbeneaththeFeMnlayershowdistinctbehaviorsbeforeandafterthePtspacerinserted.ThereisaremarkableshrinkoftheinterfacialuncompensatedspinswithintheFeMnbottominterfacialmonolayers,whereasarelaxationofthepinningstrengthoftheFeMninterfacialspinsalongtheout-of-planedirectionoccursatthetopinterface.XRDanalysisindicatesthePtlayerupontheFeMnlayerformsanfcc(002)texture,implyingthemagneticdiscrepancybetweenthetopandbottomFeMninterfaceshascrystallinestructuralorigins.
简介:TheCurietemperatureof(Nd1-xPrx)2Fe14CoyBcompounds(x=0,0.2,…,1.0andy=O,2,4,6,14)hasbeendeterminedwithACinitialsusceptibilitymeasurement.ItwasfoundthatthevariationsofCurietempera-turewithxisnotlinearfory=0and14,whereasitislinearforothervaluesofy.Thelatticeconstantsof(Nd1-xPrx)2Fet14BweredeterminedbyusingX-raydiffraction.Thelatticeexpansionwasmostlyalongthecaxis,whereasthatalongthea-axisremainedpracticallyzeroforthewholeseries.ItissuggestedthatPratomsmayshowsitepreferenceinR2M14Bcompounds(M=FeorCo).DuetothesubstitutionofCoforFe.thetendencyofsitepreferenceofPrbecomeslesspronounced,whichmaybeattributedtothedecreaseofdiffer-enceofcrystalelectricfield(CEF)actingonthetworareearthsiteswiththeintroductionofCoorFe.Incon-trasttothatofthePratoms,thesitepreferenceofCoiu(Nd(1-x)Prx)2Fe(14-y)CoyBcompoundsdoesnotdependonthecompositionoftherareearthsublattice(R=NdorPr).
简介:COandformaldehyde(HCHO)oxidationreactionswereinvestigatedovermesoporousAg/Co3O4catalystspreparedbyone-pot(OP)andimpregnation(IM)methods.Itwasfoundthattheone-potmethodwassuperiortotheimpregnationmethodforsynthesizingAg/Co3O4catalystswithhighactivityforbothreactions.ItwasalsofoundthatthecatalyticbehaviorofmesoporousCo3O4andAg/Co3O4catalystsforthebothreactionswasdifferent.AndtheadditionofsilveronmesoporousCo3O4didnotalwaysenhancethecatalyticactivityoffinalcatalystforCOoxidationatroomtemperature(20C),butcouldsignificantlyimprovethecatalyticactivityoffinalcatalystforHCHOoxidationatlowtemperature(90C).Thehighsurfacearea,uniformporestructureandtheprettygooddispersiondegreeofthesilverparticleshouldberesponsiblefortheexcellentlow-temperatureCOoxidationactivity.However,forHCHOoxidation,theadditionofsilverplayedanimportantroleintheactivityenhancement.AndthesilverparticlesizeandthereducibilityofCo3O4shouldbeindispensableforthehighactivityofHCHOoxidationatlowtemperature.
简介:【摘要】 目的 探讨卒中后抑郁( PSD)患者采用脑氢质子磁共振波谱城像( 1H-MRS)检查 N-乙酰天门冬氨酸( NAA) /肌酸( Cr)、胆碱( Cho) /Cr参数的变化及其意义。方法 选取我院收治的脑卒中患者 80例,收集时间 2016年 1月至 2017年 1月,分别于起病后 2周、 4周采用汉密尔顿抑郁量表( HAMD)进行评分,分为非抑郁组 44例、卒中后抑郁患者 36例( PSD组),选取年龄相近的 30例对象作为对照组,三组对象均接受 1H-MRS检查。结果 PSD组患者的左右侧额叶、海马 NAA/ Cr值显著的低于非抑郁组、对照组( P<0.05); PSD组患者的左右侧额叶、海马 Cho/Cr值显著的高于非抑郁组、对照组( P<0.05);中、重度抑郁组患者的左右侧额叶、海马 NAA/ Cr值显著的低于轻度抑郁组( P<0.05);中、重度抑郁患者的左右侧额叶、海马 Cho/Cr值显著的高于轻度抑郁组( P<0.05)。结论 PSD患者 1H-MRS检查会呈现左右侧额叶、海马 NAA/ Cr值降低,左右侧额叶、海马 Cho/Cr值增高的特点,并且与患者的抑郁程度有关。
简介:FormerlyNo.713Factory,HuaxingMetallur-gical&ChemicalCo.underChinaNuclearIndustryGeneralCorporationwasestablishedin1958andputintooperationin1962.ThecorporationislocatedinShangrao,JiangxiProvinceandwasoriginallydesignedtoproducerawmaterialsformillitaryuse.Inkeepingupwiththepaceofthedevelopmentofthenationaleconomy,
简介:Dopantsanddefectsareimportantinsemiconductorandmagneticdevices.Strategiesforcontrollingdopinganddefectshavebeenthefocusofsemiconductorphysicsresearchduringthepastdecadesandremaincriticaleventoday.Co-dopingisapromisingstrategythatcanbeusedforeffectivelytuningthedopantpopulations,electronicproperties,andmagneticproperties.Itcanenhancethesolubilityofdopantsandimprovethestabilityofdesireddefects.Duringthepast20years,significantexperimentalandtheoreticaleffortshavebeendevotedtostudyingthecharacteristicsofco-doping.Inthisarticle,wefirstreviewthehistoricaldevelopmentofco-doping.Then,wereviewavarietyofresearchperformedonco-doping,basedonthecompensatingnatureofco-dopants.Finally,wereviewtheeffectsofcontaminationandsurfactantsthatcanexplainthegeneralmechanismsofco-doping.